Allows you to set the horizontal and vertical sizing policies to either 'fixed' or 'resizable'.
Also lets you specify minimum and maximum sizes for the window. See the Ion.ui.SizingPolicy documentation
for details.
// Create an empty window with sizing limits
var win = new Ion.ui.Window;
win.sizingPolicy.minimumWidth = 300;
win.sizingPolicy.minimumHeight = 300;
win.sizingPolicy.maximumWidth = 800;
win.sizingPolicy.maximumHeight = 800;
// The window cannot be resized by the user to less than 300 x 300
// or more than 800 x 800

win.sizingPolicy.horizontal = 'fixed';
// Now the window can only be resized vertically

// In the main window:
var input_value, win = new Ion.ui.Window({url: 'form.html'});
win.onDataChange = function () {
input_value = win.data.value;
// do something interesting with the returned value
}
// In form.html:
// Assume this function is called when the form is submitted.
function onSubmit() {
var value = document.getElementById('value_field').value;
// This will cause the 'onDataChange' callback in the mainwindow to be executed.
Ion.ui.currentWindow.data = {value: value};
}